Should I IM him, wait for him, or just let it go?

met this guy a few months back and in the beginning everything was great. We would talk for hours at a time, we hung out one on one and also with a group. But recently he started to cancel plans at the last minute. I understand that he's busy with life. So I didn't think much of it.

But then he canceled twice in a row, when he was the one who did the asking. And I kinda got fed up with it and deleted his number from my phone and when he contacted me, I was polite but kept the conversation very short. And I think he's got the point that I'm kinda mad at him cause he stopped talking to me.

I miss talking to him as a friend.

I asked if I should IM him because like I said I deleted his number. Should I? What should I say?